Effects of Citrus aurantifolia Linn and Xylopia aethopica (Dunal) A. Rich Extracts .......... Journal of Tropical Crop Science Vol. 10 No. 1, February 2023 www.j-tropical-crops.com 17 Effects of Citrus aurantifolia Linn and Xylopia aethopica (Dunal) A. Rich Extracts on Leaf Blight Disease of Taro (Colocasia esculenta L. Schott) Ugwuja, F. N.*A, Offor, V.N.A, Akanwa, F.E.A, Achi, N.KB. and Onifade, A. K.C A Department of Plant Science and Biotechnology, Michael Okpara University of Agriculture, Umudike, Nigeria B Department of Biochemistry, Michael Okpara University of Agriculture, Umudike, Nigeria C Department of Microbiology, Federal University of Technology, Akure, Nigeria *Corresponding author; email: ugwuja.faustina@mouau.edu.ng Abstract Phytophthora colocasiae Raciborski, an Oomycete phytopathogen, has been known for several decades as the causal agent of the most infectious and devastating disease of Colocasia esculenta (L.) Schott, known as taro leaf blight (TLB). Investigations were conducted in a screenhouse to determine the effects of fruit extracts of Citrus aurantifolia and Xylopia aethiopica on the incidence and severity of TLB. The experiment was set up in a completely randomized design with three replicates. Healthy taro seedlings obtained from the National Root Crops Research Institute (NRCRI), Umudike, were planted in plastic pots (5000 cm3) containing sterilized soil enriched with poultry manure. The plant extracts were applied as foliar spray on taro leaves with a manually operated hand sprayer at 7 weeks after planting and continued at four days intervals for 28 days. Positive check was maintained with the fungicide Ridomil (a.i. mefenoxam) applied at the rate of 0.67 mg.ml-1 while zero concentration in distilled water served as negative control. Data were subjected to one-way analysis of variance, and means were separated using F-LSD. Results showed a very high reduction of disease with plant extracts (P < 0.05) and Ridomil compared to the control. Citrus aurantifolia juice was more efficient in reducing the incidence and severity of TLB compared to X. aethiopica extracts and was highly significant (P<0.05). The overwhelmingly fungitoxic effects of C. aurantifolia and X. aethiopica extracts on P. colocasiae, as expressed in the reduction of disease, suggests that these extracts can serve as alternative bio-fungicide for the control of TLB. Hence, further studies under field conditions are required to reestablish their efficacy. Keywords: disease, fungitoxic, plant extracts, Phytophthora colocasiae before plant extracts Introduction Plant disease epidemics have influenced the course of history in countries where they have had a devastating effect, and continue to be of great importance especially for those people whose day-to-day survival depends on their crops. The Phytophthora leaf blight epidemic in Nigeria in 2009 almost wiped out subsistence and large scale cocoyam production (Ugwuja and Chiejina, 2011) within two months of its incidence. Farmers in Southeast Nigeria, where the epidemic started, were alarmed at the swift destruction of their taro crops and the onset of severe scarcity and exorbitant prices of taro commodities in all the markets. Similar situations attributed to the same cocoyam leaf blight were reported in Cameroon's southwest and northwest districts (Mbong et al., 2013) and Ghana (Omane et al., 2012) where farmers could not produce enough cocoyam to eat or sell. Taro (Colocasia esculenta (L.) Schott), known as cocoyam, is one of the oldest tropical crops grown primarily for its edible starchy corms and highly nutritive leaves (Ekanem et al., 2008; Ukpabi et al., 2011) as well as for its ornamental and traditional uses (Manner and Taylor, 2011). It is an important traditional staple food for millions of people in developing countries and is a good source of carbohydrates, wax, and therapeutics. Ethno-botanical evidence suggests that taro originated in South Central Asia, probably in India or the Malaya Peninsula (Onwueme and Charles, 1994). From its center of origin, taro spread eastward to the rest of South East Asia, China, Japan and the Pacific Islands (Manner and Taylor, 2011). From Asia, taro spread westward to Arabia and the Mediterranean region. It arrived on the east coast of Africa over 2,000 years ago. Voyagers took it, first across the continent to West Africa, and Journal of Tropical Crop Science Vol. 10 No. 1, February 2023 www.j-tropical-crops.com 18 Ugwuja, F. N., Offor, V.N., Akanwa, F.E., Achi, N.K. and Onifade, A. K. later on slave ships to the Caribbean. Today taro is pan-tropical in its distribution and cultivation due to its wide adaptability, large-scale acceptability and high return per unit area. Taro also thrives well on heavy soils on which flooding and waterlogging can occur. From time immemorial, taro has been an essential daily diet for many ethnic groups in Nigeria, creating a relatively constant year-round demand as it provides an alternative source of carbohydrates to supplement yams and cassava (Echebiri, 2004; Nwachukwu and Osuji, 2008; Okereke, 2020). The scarcity of this important food crop occasioned by the recurring epidemic of taro leaf blight has tremendously increased costs beyond the reach of most people and overall demand. Phytophthora colocasiae, an oomycete phytopathogen (CABI, 2020; Otieno, 2020), has been known for several decades as the causal agent of the most infectious and devastating disease of Colocasiae esculenta commonly referred to as “taro leaf blight” (Fullerton and Tyson, 2004; Brooks 2005; Brook, 2008; Misra et al., 2008; Misra et al., 2011; Ugwuja and Chiejina, 2011; Omeje et al., 2016; Padmaja et al., 2017). Ugwuja et al. (2020) noted that the swift development of taro leaf blight infections has catastrophic consequences for both small, medium and large-scale production of taro due to the ubiquitous nature of the pathogen and the rapid rate of spread by wind-blown rain. The pathogen is also soil- borne and favored by field flooding conditions (Grade and Joshi, 2003). It is believed to have originated in South East Asia and is widely distributed throughout tropical regions (CMI, 1997). It attacks mainly the foliage, first appearing as small, brown, water-soaked spots that rapidly enlarge to form large, dark brown lesions. The lesions often coalesce to destroy a large portion of the leaf, sometimes with numerous droplets of orange or reddish exudates (Ugwuja et al., 2021). Depending on the aggressiveness of the infection, rapid and complete defoliation of leaves may occur within 14 days against 40 days normal longevity in the absence of disease (Brooks, 2008; Misra et al., 2008; Nath et al., 2015), leading to a strong hindrance of photosynthesis, stunted corms and a yield loss up to 80% (Adomako et al., 2017). Yield losses can also vary from 25-30% in some areas when the infection is mild (Miyasaka et al., 2001; Misra et al., 2011), up to 50% in severe cases (Brunt et al., 2001; Misra, 2008) and over 70% in extremely severe cases (Nelson et al., 2011; Adomako et al., 2017). Leaf yield losses can be up to 95%. The epidemic of taro leaf blight may occur throughout the year during the continuous rainy season over vast weather where night temperatures are 20 – 22oC and daily temperatures of 25 - 28oC with little seasonal variation (Mbong et al., 2013).The pathogen also causes pre-harvest and post-harvest deterioration of corms (Omeje et al., 2016) leading to the depreciation of their market value. Significant depletion in the proximate and phytochemical composition of infected corms has also been reported (Ugwuja et al., 2020). Several measures of integrated pest management have been adopted to control this disease. These include the use of cultural methods, synthetic chemicals, biological control methods, and natural plant use of natural plant extracts (botanicals). Synthetic chemicals such as sodium ortho-phenyl phenate, borax, captan, thiabendazole, sodium hypochlrorite (bleach), nordox, benomyl and mancozeb have been found to significantly reduce TLB (Mishra et al., 2008). However, the high costs of these chemicals and obvious pollution of non- target organisms have prompted investigations on exploiting pesticides of plant origin to control fungal pathogens. There has been increasing interest in using bio-pesticides to manage many plant diseases due to their relative accessibility and availability at little or no cost. These bio-pesticides are also specific, biodegradable and environmentally friendly. On the other hand, the conventional synthetic chemicals used in managing of plant diseases have continually received criticismsdue to the associated ecological and health hazards (Komarek et al., 2010; Dhaliwal and Koul 2011). Moreover, researchers have shown that a repeated exposure of fungal pathogens to fungicides can lead to resistance in the pathogen (Adomako et al., 2017). Given the many demerits of synthetic chemicals and the need to boost taro production through a sustainable disease control strategy against taro leaf blight, there should be no limit to the exploration/exploitation of readily available and biodegradable products of nature in our environment. Therefore, this study aimed to evaluate the antifungal potentials of lime, ethanol, and aqueous extracts of Xylopia aethopica on taro leaf blight disease under screenhouse conditions. Materials and Methods Study Location The study was carried out in a screenhouse at the National Root Crops Research Institute (NCRI) Umudike, Nigeria (05o 211N and 07o 331E). Sources of Materials Healthy taro corms were obtained from the Research Farm at the NCRI, Umudike, Nigeria. Materials for Effects of Citrus aurantifolia Linn and Xylopia aethopica (Dunal) A. Rich Extracts .......... Journal of Tropical Crop Science Vol. 10 No. 1, February 2023 www.j-tropical-crops.com 19 plant extracts: Xylopia aethopica (locally known as “uda”) fruit and lime (Citrus aurantifolia) fruit were obtained from the Umuahia town market. The identity of these plant materials was authenticated by the Herbarium Section of the Department of Plant Science and Biotechnology, Michael Okpara University of Agriculture, Umudike. Soil Preparation Loam soil used in this work was collected from a fallow field at the NRCRI and sterilized by heating in metallic drums at temperatures above 160ºC for 2 hours to destroy soil-borne pathogens. The sterilized soil was allowed to cool for three days and mixed with dry poultry dung at the rate of 4 g per kg of soil in order to increase the soil fertility status. The enriched soil was transferred into plastic pots (5000 cm3) in the screen house where the corms were to be planted. Thereafter, the soil was left for 7 days before the corms were planted so that heat generated during the decomposition of the poultry manure does not suffocate the corm (Fokunang et al., 2016). Experimental Design and Planting The experiment was a completely randomized design comprising three plant extracts applied in four levels (control, 10%, 20%, 30%). Healthy seedlings of a highly susceptible variety, NCe001 were planted one per plastic pot (5000 cm3) containing ¾ filled enriched loam soils in July during the 2019 planting seasons. The plants were maintained in a screenhouse and watered twice daily. Preparation of the Plant Extracts The aqueous and ethanolic plant extracts were obtained following the soaking method described by Onaebi et al. (2019) with slight modifications. Preparation of ethanolic extract of Xylopia Fifty grams of pulverized Xylopia fruits were measured into a glass bottle with a lid and soaked with 500 ml of 95 % ethanol. The mixture was stirred thoroughly and allowed to stand for three days. During this time, the mixture was stirred at least twice each day. After the third day, it was filtered into a beaker through four layers of sterile muslin cloth and covered with a perforated foil in order for the ethanol to evaporate and form a paste-like end product. Preparation of aqueous extract of Xylopia In preparing the aqueous extract of Xylopia, hot distilled water at 40ºC was used in soaking the milled sample of Xylopia fruits. The mixture thus obtained was shaken vigorously and allowed to stand for only 24 hours to prevent microbial growth and later on sieved through four layers of sterile muslin cloth. The filtrate was concentrated under a vacuum at 20-40ºC using a rotary evaporator (Model: RE – 52A) supplied by Union Laboratory, England. The crude extracts (stocks) were put into sterile screw-capped bottles, labeled accordingly, and stored in the refrigerator as long as the experiments lasted. Preparation of the lime extract Fresh lime fruits were washed, sliced into four pieces, and the juice was squeezed out into a beaker which was later sieved to remove debris and stored. Reconstitution of crude extracts One gram portion of each crude extract was mixed with 1 ml of 25% of dimethyl sulfur oxide (DMSO) in a sterile Bijou bottle; DMSO served as a binding agent to make the extract adhere or stick to the foliage surface when it was being sprayed. The mixture was stirred thoroughly and an additional 9 ml of sterile distilled water was added to form 1a 100 mg/ml stock solution of the particular extract. By means of a sterile pipette 10ml of the stock was taken and added to 90 ml of sterile distilled water in a conical flask to form 10%. Another 20 ml of the stock was added to 80 ml of sterile water to form 20%, and the last concentration 30%, was formed by adding 30 ml of stock to 70 ml of the sterile water. Fungal cultures The inoculum used in this study was obtained from previously isolated stock cultures of Phytophthora colocasiae maintained in the Phytopathology laboratory of NCRI, Umudike. Inoculation Inoculation of taro plants was done artificially with inocula obtained from a 7-day-old actively growing cultures of P. colocasiae. The cultures were grown on Cornmeal Agar (21 g of Cornmeal in 1 liter of distilled water, autoclaved under pressure at 121oC for 15 minutes) and incubated at room temperature for seven days. Thereafter spore suspension was made by pouring 10 ml of sterile distilled water to each culture plate and carefully dislodging the spore with sterile Carmel’s -hair brush and chilling at 10oC for 30 minutes to allow zoospore release (Brooks, 2008). The spore suspension was diluted and two drops were applied to the third-oldest leaves of the taro plant to cause infection. Journal of Tropical Crop Science Vol. 10 No. 1, February 2023 www.j-tropical-crops.com 20 Ugwuja, F. N., Offor, V.N., Akanwa, F.E., Achi, N.K. and Onifade, A. K. Application of Treatment The plant extract treatments were applied when the first symptoms of TLB were observed on the inoculated plants as foliage and petioles spray with a manually operated hand sprayer at seven weeks after planting (7 WAP) and continued at four days intervals for up to 28 days. Application of treatment was carried out early in the morning or evening to avoid the effect of wind which might drift extracts from their intended targets. Distilled water was sprayed on the leaves and petioles of control plants. Disease Monitoring The crops were closely monitored for initiation of disease symptoms. TLB incidence and severity were measured on the leaves of treated plants starting from the day the first symptom was noticed and continued consecutively at 4-day intervals for 28 days. Disease incidence Percent blight incidence was worked out according to the expression of Ganie et al. (2013). Disease incidence was calculated based on the total number of infected plants per total number of observed plants. PBI = PBI = X100%   X100% Where PBI = Percentage blight incidence TNIP = Total number of infected plants per treatment TNP = Total number of plants per treatment Disease severity A six-point numerical scale (0, 1, 2, 3, 4, 5) adopted from Ganie et al. (2013) was used for the assessment of disease severity. These numerical values denote the percent (%) leaf area infected as follows: 0 = No disease (0%), 2 = 1-10%, 3 = 11- 25%, 4 = 26 - 50%, 5 = 51- 75 %, 6 = > 76 %. Percent disease Intensity (PDI) was calculated following the formula given by Ganie et al. (2013): PDI = Σ (ni x vi) × 100 n x S Where, Σ = Summation; ni = number of leaves in each category; vi = score of leaves observed, and S = maximum score. Statistical Analysis Data obtained from the experiment were subjected to one-way analysis of variance, and treatment means were separated at 5% level of significance. Results Effect of Citrus aurantifolia Extracts on TLB Leaf Blight Incidence Plants treated with extracts of C. aurantifolia had significantly lower (P < 0.05) incidence than that treated with distilled water, the negative control (Table 1). Disease incidence gradually reduced as the concentration of Citrus juice extract increased. No disease was recorded on the plants treated with Ridomil, the standard fungicide and C. aurantifolia extract at 30% concentration, while the highest disease incidence 38.9% was obtained with the distilled water (zero strength of the extract). There was a remarkable reduction in disease incidence from the 12 DAI (day after infection) to the 24th day reaching zero levels at 20 and 30% concentrations. Effect of Citrus aurantifolia Extract on TLB Severity Table 2 shows the effect C. aurantifolia extract on percent leaf blight severity days after infection. Mean disease severity varied amongst the concentrations and assessment periods and was statistically (P<0.05) significant. No disease was equally observed on the plants treated with the C. aurantifolia extract at 30 % concentration as it was with the incidence while the Table 1. Effect of Citrus aurantifolia extract on TLB incidence (%) Time (DAI) Concentration (%) 4 8 12 16 20 24 0 38.9 36.1 16.7 16.1 11.1 10.0 10 33.3 25.0 20.2 10.0 6.7 3.3 20 33.3 19.4 0.0 0.0 0.0 0.0 30 16.7 6.1 0.0 0.0 0.0 0.0 LSD0.05 (Treatment): 9.21* LSD0.05 (Time): 11.28** LSD0.05 (Interaction): 22.57 NS Effects of Citrus aurantifolia Linn and Xylopia aethopica (Dunal) A. Rich Extracts .......... Journal of Tropical Crop Science Vol. 10 No. 1, February 2023 www.j-tropical-crops.com 21 highest severities (16.0) was observed on the plants treated with the distilled water. Disease severity equally decreased with increasing concentration and time as was observed earlier. Effect of Aqueous Extract of Xylopia aethopica on TLB Incidence The effect of aqueous extract of Xylopia aethopica revealed less incidence on application of high concentration (30%) than others comparing favourably with that of Ridomil (Table 3). The results showed that taro plants treated with distilled water (control) expressed significantly (P<0.05) higher disease ranging from 66.7% to 44.4% as time increased compared to the ones that received the Xylopia extract treatments at 10, 20 and 30% which had disease incidence range of 16.7- 0.0%. Reduction of disease with time observed with Xylopia extract was not as remarkable as that of the Citrus extract which had 0.0% incidences from the 12th -24th DAI under 20 and 30% concentrations. Effect of Aqueous Extract of Xylopia on TLB Severity Results showed that Plants treated with aqueous extract of X. aethopica recorded zero (0%) disease at 30 and 20% concentrations from 16- 24 DAI and 24 DAI, respectively. This result was compared favourably with that of the Ridomil but significantly differed (P< 0.05) from the ones obtained from plants treated with distilled water and extract at 10% concentration (Table 4). Effect of Ethanol Extract of Xylopia aethopica on TLB Incidence Results presented in Table 5 showed that ethanol extract of Xylopia aethopica significantly (P< 0.05) reduced the incidence of TLB compared to the control and also had a better effect than the aqueous extract in reducing disease. Similarly, in a dosage dependent pattern, disease declined as the concentration of the extract increased. There was a drastic reduction of disease amongst concentrations 10-30 % of the extract from the 12-24 DAI and a complete elimination of disease (zero incidence) at 30% concentration from12-24 DAI. This suggests that 30% concentration is the most efficient and the best concentration for the ethanol extract. Effect of Ethanol Extract of Xylopia aethopica on TLB Severity Ethanol extract of Xylopia aethopica significantly (P < 0.05) reduced disease severity compared to the control and also had a better effect than the aqueous extract in reducing disease (Table 6). Similarly, in a dosage-dependent manner, the disease was drastically eliminated to zero values as the Table 2. Effect of Citrus aurantifolia juice extract on TLB severity (%) Time (DAI) Concentration (%) 4 8 12 16 20 24 0 16.0 14.9 11.0 10.1 10.6 11.6 10 9.5 5.2 0.4 0.2 0.0 0.0 20 9.0 0.7 0.0 0.0 0.0 0.0 30 2.7 0.1 0.0 0.0 0.0 0.0 LSD0.05 (Treatment): 2.89 ** LSD0.05 (Time): 3.53** LSD0.05 (Interaction): 7.07 NS Table 3. Effect of aqueous extract of Xylopia aethiopica on TLB incidence (%) Time (DAI) Concentration (%) 4 8 12 16 20 24 0 66.7 41.7 48.9 50.0 55.6 44.4 10 19.4 19.1 18.3 11.7 8.3 3.3 20 16.7 14.4 8.3 6.7 5.0 1.7 30 16.7 12.0 6.7 3.3 3.3 0.0 LSD0.05 (Treatment): 9.92 ** LSD0.05 (Time): 12.14 NS LSD0.05 (Interaction): 24.29 NS Journal of Tropical Crop Science Vol. 10 No. 1, February 2023 www.j-tropical-crops.com 22 Ugwuja, F. N., Offor, V.N., Akanwa, F.E., Achi, N.K. and Onifade, A. K. concentration of the extract increased at 20 and 30 % on day 12 DAI and 12- 24 DAI, respectively. This suggests that 30% concentration is the most efficient and the best concentration for the ethanol extract. Discussion In several laboratory and field trials, botanical-based antifungal products are effective in the control of pathogenic fungi (Ahmed, 1998; Carabet et al., 2005; Sealy et al., 2007; Shakywar et al., 2007; Shakywa et al., 2012; Jimoh et al., 2013; Balamurugam, 2014; Sesan et al., 2017). Findings from the present study have also demonstrated the ability of extracts from the test plants to control an Oomycete pathogenic fungus, Phytophthora colocasiae through vivid reduction of incidence and severity of Phytophthora leaf blight under screen house conditions. The disease was markedly reduced in the extract treated plants than in control. This reflects the ability of the extracts to reduce the amount of inocula (infective propagules) which would have caused more infection within the screen house. Moreover, the character exhibited by the plant extracts also reflects their direct fungistatic or fungicidal effect on the causal pathogen Phytophthora colocasiae likely due to the antifungal principles reported to be present in them (Fleischer 2003; Nata’ala et al., 2018; Oikeh et al., 2015; Aibinu et al., 2007). The results are comparable to those previously obtained by earlier workers who studied the effects of these plant species on pathogenic organisms in different experiments (Balamurugam, 2014; Okigbo and Nmeka, 2005; Amadioha and Obi, 1998; Aibinu et al., 2007). Table 4. Effect of aqueous extract of Xylopia aethiopica on TLB severity (%) Time (DAI) Concentration (%) 4 8 12 16 20 24 0 12.0 6.3 9.2 9.9 5.8 5.8 10 0.4 1.7 1.0 0.3 0.3 0.1 20 3.8 2.0 1.0 0.2 0.1 0.0 30 0.1 0.1 0.1 0.0 0.0 0.0 LSD0.05 (Treatment): 2.4** (**) highly significant LSD0.05 (Time): 2.94** LSD0.05 (Interaction): 5.88 NS Table 5. Effect of ethanol extract of Xylopia aethopica on TLB incidence (%) Time (DAI) Concentration (%) 4 8 12 16 20 24 0 33.3 25.0 44 .4 44.4 38.9 41.7 10 20.1 19.4 13.3 6.7 5.0 5.0 20 16.7 11.1 5.0 5.0 5.0 5.0 30 8.3 11.1 0.0 0.0 0.0 0.0 LSD0.05 (Treatment): 10.03 ** LSD0.05 (Time): 12.28 NS LSD0.05 (Interaction): 24.57 NS Table 6. Effect of Ethanol extract of Xylopia aethopica on TLB severity (%) Time (DAI) Concentration (%) 4 8 12 16 20 24 0 30.6 26.5 22.3 21.3 19.7 20.5 10 0.4 1.6 1.7 0.8 0.4 0.2 20 2.4 2.7 0.2 0.0 0.0 0.0 30 2.4 0.1 0.0 0.0 0.0 0.0 LSD0.05 (Treatment): 4.6** LSD0.05 (Time): 5.6** LSD0.05 (Interaction): 11.3 NS Effects of Citrus aurantifolia Linn and Xylopia aethopica (Dunal) A. Rich Extracts .......... Journal of Tropical Crop Science Vol. 10 No. 1, February 2023 www.j-tropical-crops.com 23 The results illustrated in the tables show that disease incidence and severity decreased with increasing concentration of extracts indicating that the antifungal capacity of the extracts is dependent on the amount of active principle in each given concentration of crude extract. This corroborates the findings of many workers (Sagar et al., 2007; Balamurugam, 2014; Tegang et al., 2018) who reported marked concentration-dependent inhibition of phytopathogenic fungi in different studies. Although the extracts exhibited effective control of TLB, C. aurantifolia extract was the most efficient in reducing disease given the lowest (zero) percentage of disease at a 30% concentration. This suggests that 30% concentration is the absolute fungicidal dose. The differential capacity of the extracts to reduce disease could be attributed to differences in their quantitative and qualitative phytochemical composition as opined by Edeoga et al. (2005). Plants of different species vary in the type and amount of bioactive principles and their biological activities are bound to be different. The observed variation in the performance of the extracts could also be attributed to the type of solvent used for extraction (Okwu, 2006). The antifungal activity of C. aurantifolia could be ascribed to some components such as limonene and geranial which were reported to have antimicrobial activity. Two studies by Pasqua et al. (2006 and 2007) reported that limonene, the major component in citrus essential oil, had high antimicrobial activity against pathogens when applied separately. This result agrees with the results of Tchameni et al. (2017) who reported the highest inhibition of sporangia production (72.84%) by lime oil at 400 ppm. Although the aqueous and ethanol extracts of Xylopia aethiopica showed a significant reduction of disease they were not as efficient as that of C. aurantifolia in the present study. However, there are reports of the overwhelming potency of X. aethiopica against many pathogenic fungi and bacteria in different studies (Amadioha and Obi, 1998; Fleischer, 2003; Okigbo and Nmeka, 2005; Fleischer et al., 2008, Nweze and Onyishi, 2010; Tegang et al., 2018). Amadioha and Obi 1998 reported that hot water and oil extracts of Xylopia aethiopica significantly reduced spore germinatsion and growth of Colletotricum lindemuthianum in vitro. Test with cowpea (Vigna unguiculata) indicated that the extracts applied before or after infection of plant with C. lindemuthianum were also effective in reducing the size of pathogen induced lesions greater than that of Benomyl. Conclusion Our present study indicated that fruit juice of C. aurantifolia, aqueous and ethanol extracts of X. aethiopica significantly exhibited antifungal potency in controlling leaf blight disease of C. esculenta caused by P. colocasiae. The results revealed that among the extracts used, an aqueous extract of C. aurantifolia (lime juice) was the best alternative for biocontrol of taro leaf blight. This finding is the first report of these extracts in controlling Phytophthora leaf blight disease of colocasia. However, the mechanism of action of these extracts still needs further investigation in both in-vitro and field trials. Having observed the efficacy of Citrus aurantifolia aqueous extract as well as aqueous and ethanol extracts of Xylopia aethiopica on the reduction of Phytophthora leaf blight disease of taro, we therefore, recommend that farmers should adopt these extracts because of their bio-friendly and availability status. Further research should be carried out in this area to isolate the specific antifungal fractions of these extracts and make them available in commercial quantities. Acknowledgement We immensely express our gratitude to the National Roots Crops Research Institute (NRCRI) Umudike who provided the Colocasia species and the screenhouse used for this research. References Adomako, J., Kwoseh, C. and Moses, E. (2017). Metalaxyl sensitivity and aggressiveness of Phytophthora colocasiae isolates associated with taro leaf blight disease. Journal of Plant Pathology 99, 205-21. Aibinu, I., Adenipekun, T., Adelowotan, T., Ogunsanya, T., and Odugbemi, T. (2007). Evaluation of the antimicrobial properties of different parts of C. aurantifolia (lime fruit) as used locally. African Journal of Traditional, Complementary and Alternative Medicine 4, 185-190. Amadioha, A.C., and Obi, I. (1998). 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